1. Technical Field
The present invention relates to an aqueous ophthalmic composition. More specifically, the present invention relates to an aqueous ophthalmic composition having a reduced defoaming time, enhanced preservative efficacy, and improved photostability.
2. Background Art
In the field of ophthalmology, solubilizing agents are added to a variety of preparations. In particular, in aqueous ophthalmic compositions, various solubilizing agents are added for the purpose of helping dissolution of biologically active components and additives with relatively low water solubility, and the like. A surfactant can be given as an example of the solubilizing agents used in the field of ophthalmology. It is known that polyoxyethylene castor oil is a nonionic surfactant and is added to an aqueous ophthalmic composition to help dissolve other components (JP2005-298448A).
An aqueous composition containing a surfactant is known to easily foam, and foam is generated when vibration or impact is applied during production or distribution. In general, to use the aqueous ophthalmic composition in a manner safe on the eyes, the dissolution check during production is considered important. Of aqueous ophthalmic compositions, medical products such as eye drops and eye washes require foreign matter detection in the production steps. However, when foam is generated in the aqueous ophthalmic composition during production, and disappears at low speed, it is hard to distinguish active ingredients or foreign matter from the foam. Consequently, steps such as dissolution check and foreign matter detection take a long period of time, which prevents efficient production.
Further, it is desirable that an aqueous ophthalmic composition prevents a product from spoiling due to microbial contamination or the like during use. Therefore, an antiseptic is added to each aqueous composition for the purpose of preventing spoiling to ensure preservation stability of the aqueous composition. However, in general, nonionic surfactants are known to have an effect of inactivating antiseptics to reduce antiseptic action. Accordingly, preservative efficacy in a composition containing a nonionic surfactant is predicted to be insufficient.
Moreover, it is important for aqueous compositions to ensure stability during production and market circulation, and long-term stability after opening. Therefore, an adverse effect on quality by the decomposition of components due to light exposure cannot be ignored. Hence, a method for stably preserving a solution for a long period of time while preventing photodecomposition is desired.
On the other hand, to improve the properties of aqueous ophthalmic compositions, addition of vegetable oil has been attempted. For example, as a method for stabilizing the viscosity of a composition, JP2006-117656A discloses a sesame oil-containing composition that is applicable to mucous membranes.
However, effects on the defoaming time, preservative efficacy, and photostability attained by adding sesame oil to an aqueous ophthalmic composition have not yet been clarified. In particular, an effect on an aqueous ophthalmic composition provided when these components and a specific surfactant are added to the aqueous ophthalmic composition cannot be easily predicted.